Since Bane wanted to break Gotham's spirit first I could see him using the Joker for that end.The Joker would'nt know about Bane's true agenda and thus be misled in to helping the "revolution".In the end the bomb explodes and everyone dies.

It's a victory for both since Bane wants to die and Joker does'nt care about dying.

But if you're talking about a vs situation then the Joker gets owned bad,the only thing saving him from a complete beat down is the power of the screen writer/plot device which he had tons of in TDK.

He would care more than anyone (except Batman) if he and all city will die because some other maniac's (Ra's) ideal to fight with corruption. Joker wants corruption to boost chaos.. while Ra's wants to end it. I wouldn't surprise if Joker helps Batman to stop Bane.

I think he only doesn't care about dying if his death serves chaos. (Like he pushed Batman & Harvey to kill him)